HUNTINGTON, Utah -- Rescuers drilling a communications hole down to six miners in a collapsed Utah coal mine said they should reach the cave-in site by Friday.

Two holes are being drilled at the Crandall Mine near Huntington, one being 2 1/2 inches for a communications line and the second being almost 9 inches to allow for delivery of food and water, USA Today reported.

The mine's general manager, Lane Adair, said the smaller hole was down 1,000 feet by 11:30 p.m. Wednesday, and was expected to reach the full 1,500 feet by Friday, barring any seismic interruptions such as ground shifts.

The larger hole was just 100 feet down, but drilling was expected to catch up to the smaller bore.

It's still unknown if the miners survived the collapse early Monday morning, but officials said no effort will be spared to get them out.

It's also unclear whether an earthquake caused the collapse, or the event that registered 3.9 on the Richter scale was the collapse itself.